Embodiments of the present invention generally relate to storage covers, and more particularly to tarp covers.
Various types of protective covers have been developed for covering piles or mounds of particulate material, such as salt, sand, grain and the like, from the effects of the weather while the material is in outside storage.
While prior art covers are capable of protecting a pile or mound of materials covered thereby, they possess a number of shortcomings. For example, in order to counteract the effects of aerodynamic lift exerted on such cover by the wind, a large number of ballast weights, such as automobile tires, were attached to the cover at fixed attachment points so that the ballast weights rested on the cover between the top or apex and the lower margin of the pile. However, if the pile had an atypical size or shape, the height of the pile diminished, or as particulate matter was removed from the pile, the fixed attachment points ended up so close to the ground that the ballast weights rested on the ground which reduced or eliminated the effectiveness of the weights in maintaining the cover on the pile.
The wind may also enter beneath the cover through a removal opening or otherwise get beneath the cover and exert tensile forces on the cover. In addition, the canvas material would develop rips if the stress became too great. However, once a canvas panel formed a rip, the rip had a tendency to propagate and extend the entire length of the panel, resulting in a substantial cost to repair the rip. Such ripping may also occur in vinyl or polyethylene panels of a cover under certain stress conditions.
Bulk storage pile covers have been in use for a long time. However there are some problems holding the covers down. The covers attach around the perimeter and in some cases also attach in the center. The cover is then held down by vacuum fans. Relying on vacuum fans to hold down the covers leaves them vulnerable to power outages. Any interruption in electrical service leaves the cover subject to damage, although some users have backup generators and others have tried external strapping systems. When used, external strapping systems are installed after the piles are full. However, new worker safety regulations on the use of fall protection, limits the use of external strapping systems.
Thus, there is a need for a cover for a pile of particulate material which protects the pile from the elements and resists the effects of wind and rain on the cover. A related need is for a cover which allows for the attachment of ballast weights at desired locations on the cover and also allows for each ballast attachment point to be shifted, compensating for changes in the shape and height of the pile.
There is a further need for a cover for a pile of particulate material which prevents rips which may form in the panels compromising the cover from propagating for more than a desired short length that is easy to repair.